Rocky intertidal ecosystems in California have been significantly degraded. Of particular concern is the precipitous population decline of rockweeds attributed to increased urbanization and accompanying impacts. As foundation species, rockweeds modify the physical environment of rocky intertidal habitats and increase biodiversity by decreasing environmental stress under their canopy. No substitute macrophyte species in southern California provides comparable function to rockweeds in the intertidal zone. Recovery of impacted rockweed populations is typically slow and unpredictable, due to their poor dispersal capacity. We propose to restore impacted rockweed across a broad spatial region in California to achieve stable and persistent populations that provide key ecosystem functions and benefits to rocky intertidal ecosystems. We will quantitatively evaluate the success of the restoration and cascading effects on intertidal communities.